It's extremely normal. As a young woman, you are more likely to have complications than, say, a woman in her mid-twenties. Not only is your body not 100% mature yet, but you're smaller, and have a lot of persecution that adults don't have concerning teen pregnancy.
Your symptoms all seem to be normal. For nausea, I suggest sour patch kids or similar. Backpain and difficulty breathing is also fairly normal, but you should definitely insist on seeing the doctor if you think you need one.
I don't really understand what the question is...? If your doctor won't tell you anything, then get a new doctor! You need someone to be open with you, and you need to be informed! Because you're so young, you need to be so so so so careful about your body and the health of the baby and yourself.
Concerning the fact that you don't want to eat anything, well, I can sympathize with that feeling. But you .N.E.E.D to have some intake of nutrition! It's sooo critical! It may be hard to have food, but you need to eat. If you keep puking up your meals, though, you need to ask a doctor.

Hope that helped a bit. :)

- mattea

Hi i'm 16 weeks and look about 6 months gone. I guess everyone shows quicker and grows at different rates during each pregnancy. The sickness should go but in the meantime try dry toast or ginger snaps.